In the past, 40-inch (″) class TVs were prevalent, but many consumers now purchase 50″ class TVs and even 60″ class TVs. While the size competition was over, resolution competition has begun. Even a year ago, full high definition (FHD) class TVs belonged to an advanced model, but ultra HD (UHD) TVs now have been rapidly spread on the market.
Recently, the display market has evolved from large-area, high-resolution competition to color competition. For this reason, competition for the production of a display with excellent color has recently emerged.
A liquid crystal display displays an image by using optical properties of liquid crystals, wherein, since a liquid crystal panel displaying the image is a non-emissive device or not self-luminous, the liquid crystal display has a structure comprising the liquid crystal panel as well as a back-light unit which is disposed on a rear surface of the liquid crystal panel to provide light to the liquid crystal panel. Although the liquid crystal display is in the spotlight as a display device used in mobile devices, computer monitors, and high-definition televisions (HDTVs), the liquid crystal display is somewhat inferior to other types of displays in terms of color.
Recently, the employment of a quantum dot sheet comprising quantum dot particles shows the best performance among various solutions proposed for realizing a high-quality color reproduction display (see Korean Patent Application Laid-open Publication Nos. 2014-056490 and 2013-123718). However, under the circumstances that a picture quality standard has been changed for UHD broadcast, a high-quality color reproduction level achievable by the quantum dot sheet is insufficient for the standard. Specifically, the quantum dot sheet may satisfy 100 percent a standard for HD TV (i.e., BT.709), or a standard for digital cinema (i.e., DCI-P3), but only reaches a level of 70% to 80% of BT.2020 as a new standard for UHD TV.
Thus, there is a need to develop a new technique which may dramatically improve a color gamut of a conventional LCD to the level of the new standard.